Lowpass resonator and particulate filter for a pressure transducer

ABSTRACT

The disclosed technology includes a transducer assembly having a first transducer element. The transducer assembly includes a first filter element adjacent to least of portion of the first transducer element such that a first cavity is defined between the first filter element and the first transducer element. The first filter element includes a plurality of machined passageways in communication with the first cavity. The transducer assembly also includes an inlet passage having a first end in communication with a first external portion of the transducer assembly and a second end in communication with the plurality of machined passageways.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 62/375,467, filed on 16 Aug. 2016, the contents of which arehereby incorporated by reference in their entirety as if presentedherein in full.

TECHNICAL FIELD

The disclosed technology relates to a pressure transducer assemblyconfigured with a mechanical low pass resonator and a particulate filterhaving multiple passageways for the measurement media to enter thetransducer.

BACKGROUND

The frequency response of pressure transducers can be criticallyimportant for many measurements. In some applications, it is importantto have very fast response times such that transient pressure phenomenamay be measured. However, in other applications, it may be important toslow down or reduce transients in the applied pressures to insure thelong-term survivability of the pressure transducer. In fuel andhydraulic systems there is often a steady state pressure that isimportant to monitor; however, in addition to this steady statepressure, there are dynamic pressure associated with pump ripple, valveopening and closing, etc. The dynamic pressures may be many times thesteady state pressure and their frequencies are often such that they canexcite the resonant frequency of the tubing. This resonance excitationcan further amplify the dynamic pressures and cause them to permanentlydamage the pressure transducer, particularly if the transducer isdesigned to monitor the relatively low static pressure.

There are many different transducer structures designed to mitigatethese dynamic pressures. Adding a pressure snubber or resonator in thefront of the transducer is the most common way to control pressureamplitudes at certain frequencies. There are also transducer housingdesigns, such as described in U.S. Pat. No. 9,116,056 that can eliminateor reduce transients. Such transducer designs often rely on a singlenarrow path (with or without an in-line sintered/porous filterstructure) in communication with a cavity to act as a Helmholtzresonator, with resonance characteristics designed such that highfrequency pressure components are attenuated. Such designs can workquite well, but a filter having a single path and/or an in-line porousfilter can become clogged over time when particulates in the measurementmedia accumulate. Such a clogged path/filter can cause the transducer tomalfunction.

BRIEF SUMMARY

The disclosed technology relates to pressure transducers and, inparticular, to a pressure transducer assembly that includes a mechanicalfilter element having multiple machined passageways for which themeasurement media may traverse. The filter element disclosed herein mayenable a pressure transducer to operate reliably, even when a portion ofthe multiple passageways become blocked or clogged.

According to an example implementation of the disclosed technology, atransducer assembly is provided. The transducer assembly includes afirst transducer element. The transducer assembly further includes afirst filter element adjacent to at least a portion of the firsttransducer element such that a first cavity is defined between the firstfilter element and the first transducer element. The first filterelement includes a plurality of machined passageways in communicationwith the first cavity. The transducer assembly also includes an inletpassage having a first end in communication with a first externalportion of the transducer assembly and a second end in communicationwith the plurality of machined passageways.

The disclosed technology includes a method for making a transducerassembly. The method can include machining multiple passageways in afilter element, and installing the filter element in a transducerassembly between an inlet port and a transducer.

Other implementations, features, and aspects of the disclosed technologyare described in detail herein and are considered a part of the claimeddisclosed technology. Other implementations, features, and aspects canbe understood with reference to the following detailed description,accompanying drawings, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a standard pressure transducer 100 having a single narrowpath and porous-type mechanical filter 104 in line with the inlet port108.

FIG. 2 depicts a pressure transducer assembly 200 according to anexample implementation of the disclosed technology. The pressuretransducer 200 includes a filter element 203 having multiple passageways206 to prevent clogging.

FIG. 3 is an inset view 300 of a portion of FIG. 2, depicting exampleparticulate matter 302 restricted by the filter element 203 fromreaching the cavity 205 adjacent the transducer element 220.

FIG. 4 is a flow diagram of a method 400, according to an exampleimplementation of the disclosed technology.

DETAILED DESCRIPTION

Although many embodiments of the disclosed technology are explained indetail, it is to be understood that other embodiments are contemplated.Accordingly, it is not intended for the disclosed technology to belimited in scope to the details of construction and arrangement ofcomponents set forth in the following description or illustrated in thedrawings. The disclosed technology is capable of other embodiments andof being practiced or carried out in various ways. Also, in describingthe preferred embodiments, specific terminology will be resorted to forthe sake of clarity.

As discussed herein, the term “filter” is intended to refer to amechanical element that can prevent passage of particles of a certainpredetermined size and larger. As discussed herein, the term “resonator”is intended to refer to a structure having an inlet, an outlet, and acavity there between, which may be used to control pressure phase and/oramplitude. An example resonator structure is a Helmholtz resonator,which may be utilized to attenuate certain pressure oscillationfrequencies. To avoid confusion, the terms “filter” or “filtering,”(which have traditionally been used interchangeably to refer to suchresonance control) will be reserved herein to refer to particulateblocking, even though the mechanical filter disclosed herein may formpart of a resonator structure.

Referring now to the figures, in which like numerals represent likeelements, certain example implementations of the disclosed technologyare described herein. It is to be understood that the figures anddescriptions have been simplified to illustrate elements that arerelevant for a clear understanding, while eliminating, for purposes ofclarity, many other elements found in typical pressure sensor assembliesand methods of making and using the same. Those of ordinary skill in theart will recognize that other elements may desirable and/or required forimplementation. However, because such elements are well known in theart, and because they do not facilitate a better understanding of thedisclosed technology, a discussion of such elements is not providedherein.

According to certain example implementations, a transducer assembly isdisclosed for measuring one or more parameters or properties associatedwith an input condition stream. The term “condition stream” as usedherein may refer to a measurement medium, such as a liquid or a gas. Thetransducer assembly may be configured to measure pressure and/ortemperature associated with the condition stream. For example, in oneillustrative embodiment, the transducer assembly may be configured tomeasure the dynamic and/or static oil pressure within a machine. Incertain example implementations, the condition stream may includeparticulate matter. Certain example implementations of the disclosedtechnology may include features that can reduce, minimize, or eliminateparticulate clogging within the transducer assembly.

Certain example implementations of the disclosed technology can includea transducer assembly having one or more multi-passageway filterelements disposed between the inlet port and the transducer. In certainexample implementations, the filter element may be part of a lowpassresonator, such as a Helmholtz resonator. In certain exampleimplementations of the disclosed technology, the multiple passagewaysdefined in the filter element may help reduce clogging, for example dueto particulates in the condition stream. According to an exampleimplementation of the disclosed technology, the multiple passagewaysdefined in the filter may be machined such that precise control of thepassageway diameters may be achieved.

FIG. 1 shows a standard pressure transducer 100 in which a mechanicalfilter element 104 is disposed in-line with the main inlet port 108(with a similar filter element 105 shown disposed in-line with areference port 110). In some designs, the mechanical filters 104 105 maybe a sintered metal filter, or other type of porous mechanical structureused to restrict the path of fluid. In other designs, the mechanicalfilters 104 105 may include a single, small diameter path to restrictthe path of fluid. The filters 104 105 can be either brazed or press fitin-line with the respective ports 108 110. In this example, a pressureheader 101 is welded onto a pressure port 102 to form a cavity 103. Therestricted path, along with the cavity 103 forms a Helmholtz resonator.When the fluid viscosity is high enough (such as with fuel or hydraulicfluids) the resonator acts as a damper for high frequencies (typicallyover a few hertz). In some designs, the reference filter 105 may bedisposed in the path of the reference port 110 and, together with thesecond cavity 106, may form another resonator structure. This allows fora differential measurement where both pressures are attenuated.Depending on the particular application this reference port 110 orfilter 105 may or may not be necessary.

FIG. 2 depicts an example pressure transducer assembly 200 in accordancewith the disclosed technology. In an example implementation, a firstfilter element 203 may be disposed in a cavity 212 defined between thepressure port 202 and the pressure header 201, for example, so that themedium traversing through the inlet passage 204 may flow into the cavity212, through multiple passageways 206 defined in the first filterelement 203, and to a transducer element 220 disposed on the pressureheader 201. According to an example implementation of the disclosedtechnology, the first filter element 203 may be attached to the pressureport 202 by one or more welds and/or other suitable means of attachment,such as press-fit, threads, adhesives, etc. Similarly, the pressureheader 201 may then be attached to the pressure port 202 (with the firstfilter element 203 disposed there between) by one or more welds and/orother suitable means of attachment, such as press-fit, threads,adhesives, etc.

In an example implementation, the pressure port 202 can include a singlelarge diameter inlet passage 204 in communication with the cavity 212;the cavity 212 may be in communication with the first filter element203; and the first filter element 203 may be in communication with thepressure header 201 and the transducer element 220. According to anexample implementation of the disclosed technology, a cavity 205 (suchas a Helmholtz cavity) may be formed between the transducer element 220and the first filter element 203.

In an example implementation, the first filter element 203 may includewell defined, multiple narrow passageways 206 that allow the measurementmedium to flow between the first cavity 212 and the cavity 205 adjacentthe transducer element, while restricting particulate matter. In certainexample implementations, the passageways 206 may be machined, drilled,or the like, for example, to control rejection of particulate matter ofa given size or larger. According to an example implementation of thedisclosed technology, the multiple passageways 206 defined in the firstfilter 203 (and/or in the multiple passageways 211 defined in the secondfilter 209) may be machined such that precise control of the passagewaydiameters may be achieved. In this respect, the passageways 206 may bemachined with controlled size and controlled distribution for a givenapplication, rather than having to rely upon (an uncontrolled) passagesize and distribution of a typical sintered or otherwise porous filterstructure.

FIG. 2 depicts the first filter element 203 with only two passageways206, however, according to certain example implementations of thedisclosed technology, there may be many more passageways 206 (not shown)defined around the circumference or other regions of the first filterelement 203 to provide additional paths through the first filter 203.This may be particularly advantageous in the event that some of thepassageways 206 become clogged. In certain example implementations, (aswill be explained below with reference to FIG. 3) one or more particletrapping recesses and/or channels may be machined into the filter 203,for example, to capture and hold certain particles.

In accordance with certain example implementations of the disclosedtechnology, the multiple small passageways 206 defined in the firstfilter element 203 in combination with at least the second cavity 206form a tunable Helmholtz resonator, which can be made to attenuatehigher frequencies depending on the viscosity of the media and geometryof the system. By virtue of the multiple passageways 206, even if one orseveral of the passageways 206 become clogged, the transducer assemblywill continue to function properly, although the cut-off frequency maychange. In many applications, the exact value of the cut-off frequencyis not important, so clogging of one or more passageways 206 may notappreciably impact the usability of the transducer assembly 200, whichmay operate with suitable results even if one or several of thepassageways 206 become clogged.

With continued reference to FIG. 2, and in an example implementation ofthe disclosed technology, the pressure transducer assembly 200 may beconfigured so that it is capable of also measuring a reference pressure.For example, a reference pressure at a reference port 222 may be routedthrough a reference tube 208, through a second filter element 209, andto a transducer. In certain example implementations, the referencepressure may be routed to the back side of the transducer element 220 toprovide a differential measurement. In other example implementations, asecond transducer (not shown) may be utilized to measure the filteredreference pressure.

In certain example implementations, the second filter element 209 may bedisposed on an opposite end of the pressure header 201 (i.e., oppositethe first filter element 203). In certain example implementations, athird cavity 213 may be defined between the second filter element 209and the pressure header. According to an example implementation of thedisclosed technology, a cap 207 may be attached to the pressure header201 and a fourth cavity 210 in communication with the reference tube 208may be defined between the cap 207 and the second filter element 209.Depending on the configuration of the transducer assembly 200, thereference pressure may be routed to the fourth cavity 210 from adifferent reference port (not shown) disposed on the side or back of thetransducer assembly 200. In certain example implementations, the secondfilter element 209 may be omitted, as it may not be needed for allapplications.

In a similar manner as described above with reference to the firstfilter element 203, the second filter element 209 may also includemultiple small machined passageways 211, which may allow taking areference pressure measurement with suitable results even if a portionof the passageways 211 become clogged.

FIG. 3 is an inset view 300 of a portion of FIG. 2 (see dashed box, FIG.2), depicting example particulate matter 302 that may be restricted bythe filter element 203 from reaching the cavity 205 adjacent to thetransducer element 220. Also depicted in FIG. 3, certain exampleimplementations may include one or more particle trapping recesses 312and/or particle diversion channels 304 to capture and hold certainparticles to further reduce clogging. For example, the diversion channel304 may include a small “holding area” past the entrance of thepassageways 206 for which certain medium sized particles 308 may gatherwithout blocking the entrance to the passageways 206. In certain exampleimplementations, one or more particle trapping recesses 312 may bemachined into the surface of the filter element 203 (and/or in thesurface of the pressure port 202). According to an exampleimplementation of the disclosed technology, the particle trappingrecesses 312 may be machined with a size (or distribution of sizes)suitable for trapping particles of a given size, such as largerparticles 310.

As depicted in FIG. 3, small particles 306 (that are smaller than thediameter of the passageways 206 of the filter element 203) may beallowed to freely move within the structure, and may end up within thecavity 205 without harming the transducer element 220. As discussedherein, particles having dimensions greater than the dimensions of thepassageways 206 may be retained, trapped, or blocked.

In one example implementation, a diameter of one or more of thepassageways 206 may be 1-5 micrometers. In another exampleimplementation, a diameter of one or more of the passageways 206 may be10-20 micrometers. In another example implementation, a diameter of oneor more of the passageways 206 may be 20-100 micrometers. In anotherexample implementation, a diameter of one or more of the passageways 206may be 100-500 micrometers.

One advantage of the disclosed technology over previous structures isthat the Helmholtz filters on either side of the pressure header 201 maybe formed using similar sized cavities, so it is much easier to matchthe attenuation of the two Helmholtz filters. Certain previous designsrequired excess tubing between the reference filter and header than frommain filter and header making it difficult to match the frequencyresponse. In some application it is important to match this response sothat there is no phase delay at low frequencies of interest.

FIG. 4 is a flow diagram of a method 400, according to an exampleimplementation of the disclosed technology. In block 402, the method 400includes machining multiple passageways in a first filter element. Inblock 404, the method 400 includes installing, adjacent to a firsttransducer in a transducer assembly, the first filter element. In block406, the method 400 includes configuring, based on a first tuningparameter, a portion of an inlet port to set a first volume of a firstvolume of a first cavity. In block 408, the method 400 includesinstalling the inlet port adjacent to the first filter element to definethe first cavity.

Certain example implementations can include machining multiplepassageways in a second filter element, and installing, adjacent to asecond transducer in the transducer assembly, the second filter element.

Some example implementations may include configuring, based on a secondtuning parameter, a second volume of a second cavity that my be definedby and/or in communication with a portion of a cap and a portion of thesecond filter element. Certain example implementations includeinstalling the cap adjacent to the second filter element to define thesecond cavity.

In some example implementations, the first tuning parameter and thesecond tuning parameter may be substantially equivalent.

According to an example implementation of the disclosed technology,machining the multiple passageways can include drilling correspondingmultiple holes through at least a periphery of the filter element. Incertain example implementations, and as depicted by the right anglepassageways 206 in FIGS. 2 and 3, machining the multiple passageways caninclude machining first multiple bores into a first side of the filterelement 203 such that the first multiple bores extend partially throughthe filter element 203 (to define, for example, the vertical portion ofthe passageway 206). The passageways may be completed by machiningcorresponding second multiple bores into a second side of the filterelement and extending partially through the filter element (to define,for example, the horizontal portion of the passageway 206) such that thefirst and second multiple bores join to form corresponding passagewaysthrough the filter element.

According to an example implementation of the disclosed technology, atransducer assembly is provided. The transducer assembly includes afirst transducer element. The transducer assembly further includes afirst filter element adjacent to least of portion of the firsttransducer element such that a first cavity is defined between the firstfilter element and the first transducer element. The first filterelement includes a plurality of machined passageways in communicationwith the first cavity. The transducer assembly also includes an inletpassage having a first end in communication with a first externalportion of the transducer assembly and a second end in communicationwith the plurality of machined passageways.

In certain example implementations, the inlet passage is configured toreceive a first incoming condition stream from the first externalportion of the transducer assembly and to channel the first incomingcondition stream to the first filter element. In certain exampleimplementations, the first filter element is configured to channel thefirst incoming condition stream through the plurality of machinedpassageways to the first cavity and the first transducer element.

In certain example implementations, the plurality of machinedpassageways are configured to restrict movement of particulate matter infirst incoming condition stream from at least the inlet passage to thefirst cavity.

According to an example implementation of the disclosed technology, thefirst transducer element is configured to measure the first incomingcondition stream.

In certain example implementations, the volume of the first cavity isset based on tuning parameters for the transducer element, wherein thetuning parameters comprise at least damping.

According to an example implementation of the disclosed technology, thefirst filter element can include one or more particle trapping recesses.

According to an example implementation of the disclosed technology, thefirst filter element can include one or more particle diversionchannels.

In an example implementation, the plurality of machined passageways areconfigured with predetermined dimensions.

Certain example implementations may further include a second transducerelement, a second filter element adjacent to at least of portion of thesecond transducer element such that a second cavity is defined betweenthe second filter element and the second transducer element, wherein thesecond filter element comprises a plurality of second machinedpassageways in communication with the second cavity, and a referencetube having a first end in communication with a first external portionof the transducer assembly and a second end in communication with theplurality of the second machined passageways.

In some embodiments, the reference tube may be configured to receive asecond incoming condition stream from the second external portion of thetransducer assembly and to channel the second incoming condition streamto the second cavity.

According to an example implementation of the disclosed technology, thefirst transducer element and the second transducer element aresubstantially identical in configuration.

In certain example implementations, the first transducer element and thesecond transducer element may be the same element.

According to an example implementation of the disclosed technology, thefirst sensing element and second sensing element are pressure sensingelements.

In some implementations, the first cavity and the second cavity aresubstantially identical in configuration.

It shall be understood that the transducer assembly described herein maybe configured to sense and measure an applied condition from an incomingcondition stream, for example but not limited to, temperature and/orpressure. It shall be further understood that each sensing elementwithin the transducer assembly may be configured to measure a differentcondition, or alternatively, measure the same condition under differentranges. For example, a first sensing element may measure pressure and asecond sensing element may measure temperature. As another example, afirst sensing element may measure pressure having a first range and asecond sensing element may measure pressure having a second range. Oncethe sensing element measures an applied condition, it outputs a signalindicative of the applied condition to an external device.

Also, in describing the many embodiments, certain terms have been usedfor the sake of clarity. It is intended that each term contemplates itsbroadest meaning as understood by those skilled in the art and includesall technical equivalents which operate in a similar manner toaccomplish a similar purpose.

The mention of one or more method steps does not preclude the presenceof additional method steps or intervening method steps between thosesteps expressly identified. Similarly, it is also to be understood thatthe mention of one or more components in a device or system does notpreclude the presence of additional components or intervening componentsbetween those components expressly identified.

It will be apparent to those skilled in the art that modifications andvariations may be made in the apparatus and process of the presentinvention without departing from the spirit or scope of the invention.It is intended that the present disclosure cover the modification andvariations of the technology within the scope of the appended claims andtheir equivalents.

What is claimed is:
 1. A transducer assembly, comprising: a firsttransducer element; a first filter element adjacent to at least aportion of the first transducer element such that a first cavity isdefined between the first filter element and the first transducerelement, wherein the first filter element comprises a plurality ofmachined passageways in communication with the first cavity; and aninlet passage having a first end in communication with a first externalportion of the transducer assembly and a second end in communicationwith the plurality of machined passageways.
 2. The transducer assemblyof claim 1, wherein the inlet passage is configured to receive a firstincoming condition stream from the first external portion of thetransducer assembly and to channel the first incoming condition streamto the first filter element, and wherein the first filter element isconfigured to channel the first incoming condition stream through theplurality of machined passageways to the first cavity and the firsttransducer element.
 3. The transducer assembly of claim 2, wherein theplurality of machined passageways are configured to restrict movement ofparticulate matter in the first incoming condition stream.
 4. Thetransducer assembly of claim 2, wherein the first transducer element isconfigured to measure the first incoming condition stream.
 5. Thetransducer assembly of claim 1, wherein a volume of the first cavity isset based on tuning parameters for the transducer element, wherein thetuning parameters comprise at least damping.
 6. The transducer assemblyof claim 1, wherein the first filter element comprises one or moreparticle trapping recesses.
 7. The transducer assembly of claim 1,wherein the first filter element comprises one or more particlediversion channels.
 8. The transducer assembly of claim 1, wherein theplurality of machined passageways are configured with predetermineddimensions.
 9. The transducer assembly of claim 1, further comprising: asecond transducer element; a second filter element adjacent to at leastof portion of the second transducer element such that a second cavity isdefined between the second filter element and the second transducerelement, wherein the second filter element comprises a plurality ofsecond machined passageways in communication with the second cavity; anda reference tube having a first end in communication with a firstexternal portion of the transducer assembly and a second end incommunication with the plurality of the second machined passageways. 10.The transducer assembly of claim 9, wherein the reference tube isconfigured to receive a second incoming condition stream from the secondexternal portion of the transducer assembly and to channel the secondincoming condition stream to the second cavity.
 11. The transducerassembly of claim 9, wherein the first transducer element and the secondtransducer element are substantially identical in configuration.
 12. Thetransducer assembly of claim 9, wherein the first transducer element andthe second transducer element are the same element.
 13. The transducerassembly of claim 9, wherein the first sensing element and secondsensing element are pressure sensing elements.
 14. The transducerassembly of claim 9, wherein the first cavity and the second cavity aresubstantially identical in configuration.
 15. A method, comprising:machining multiple passageways in a first filter element; installing,adjacent to a first transducer in a transducer assembly, the firstfilter element; configuring, based on a first tuning parameter, aportion of an inlet port to set a first volume of a first cavity; andinstalling the inlet port adjacent to the first filter element to definethe first cavity.
 16. The method of claim 15, further comprising:machining multiple passageways in a second filter element; installing,adjacent to a second transducer in the transducer assembly, the secondfilter element.
 17. The method of claim 16, further comprising:configuring, based on a second tuning parameter, a cap to set a secondvolume of a second cavity; and installing the cap adjacent to the secondfilter element to define the second cavity.
 18. The method of claim 17,wherein the first tuning parameter and the second tuning parameter aresubstantially equivalent.
 19. The method of claim 15, wherein machiningthe multiple passageways comprises drilling corresponding multiple holesthrough at least a periphery of the first filter element.
 20. The methodof claim 15, wherein machining the multiple passageways comprises:machining first multiple bores into a first side of the first filterelement and extending partially through the first filter element; andmachining corresponding second multiple bores into a second side of thefirst filter element and extending partially through the first filterelement, wherein the first and second multiple bores join to formcorresponding passageways through the first filter element.